The long term objective is to develop commercial applications of newer biotechnological methods for vaccine development to eliminate problems resulting from diseases caused by herpesvirus. It is proposed to use the "Marek's Disease System" as an animal, virological and molecular model for research on oncogenic and other diseases caused by herpesviruses. Marek's disease is a neoplastic disease of chickens causing significant economic losses. It is caused by a herpesvirus (MDHV) but can be ameliorated by immunization with the non-pathogenic herpesvirus of turkeys (HVT). Phase I research will focus on the prominent A antigens common to MDHV and HVT. Aim No. 1 is to complete molecular characterization of the polypeptide of the MDHV-A and HVT-A glycoprotein antigens. Methods of analysis will include size comparison on SDS-PAGE, staphylococcal V8 protease degradation and tryptic peptide analyses. Aim No. 2 is to identify the cloned MDHV restriction DNA fragment(s) encoding the polypeptide(s) of the common A antigens by hybrid selection of mRNA, cell-free translation of the mRNA and hybrid arrest of that translation. Results of Phase 1 should provide the genetic information encoding a well characterized antigen in a cloned DNA form. Phase II would proceed with either expression of the genetic information in a bacterial expression vector, or chemical synthesis of immunogenic peptides.